Jordan forced me to give you feedback..
Overall,
I will say stuff a critic would say so don't get upset, it's just my own opinion and throughout the feedback I will give you advice on how to improve it and the cons (bad things) about your work. First of all, The font doesn't fit in the theme, try using a destroyed font or adding a claw rubber to give it a feel of your theme as in your fact it is a demon. The following font you used is more a pirate font which reminds me of Piratebay.
Secondly, try adding highlights on your demon and using the adjustments on he top right like Curves, Exposure, etc. Test all of them. Try to find a proper area to place your slogan because it would look great if you added the slogan somewhere under your name without the rectangle.
Thirdly, the pattern you used with the diagonal lines, is very shit and does not fit at all because it's white and the rest of the thing is black-themed. It does not fit at all like I mentioned before and to fix that you can copy some textures and create a clipping mask on the text and set the blending options to "Overlay". It will make your work look amazing and I suggest for you to check out some tutorials and below I will give you links to some Youtubers that create great Photoshop tutorials.
Fourthly, the profile picture is extremely simple, like I could create it in 20 seconds, literally.. Copy and paste and get the text tool, then write "John Satanic" and to fix that you will need to use a better font, add more effects and be more creative. All you did in the profile picture, add a piratebay font and done. You need effort and time. Creativity is key to Graphic success. When I create my artwork, I try to get inspired by watching Speedart videos and watching my favourite German youtuber. Go to Youtube search bar and write
"photoshop speedart banners" or
"photoshop speedart gfx" and trust me, you will get inspiration but try to combine your ideas and you will eventually create something fantastic. Trust me. I've been doing Graphic Designing for 5+ Years and I have a lot of experience with this sort of work. It is your choice, you can listen to my advice and use it or ignore it. Thanks for reading and hope you found this helpful.
Links :
MoltenPixelTV - It is a German speaking channel but he is talented you can find here, speedarts, tutorials and his GFX Pack.
Udemy - Courses are good to learn stuff, they are free and some are payable. Helped me, will help you. You will have to sign up to access their course album.